Learning and plasticity in the human brain

人脑的学习和可塑性

• 批准号: 8556969
• 负责人: Christopher Baker
• 金额: $ 35.15万
• 依托单位: NATIONAL INSTITUTE OF MENTAL HEALTH
• 依托单位国家: 美国
• 资助国家: 美国
• 起止时间: 至
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/8556969
• 关键词: Adult; Amputation; Amputees; Blindness; Brain; Brain Part; Brain region; Characteristics; Conflict (Psychology); Decision Making; Development; Disease; Elderly; Esthesia; Feeling; Functional Magnetic Resonance Imaging; Functional disorder; Goals; Human; Impairment; Injury; Judgment; Lead; Learning; Limb structure; Macular degeneration; Measures; Modeling; Monitor; Motion; Motor Cortex; Nature; Nervous System Trauma; Nervous system structure; Pain; Participant; Patients; Perceptual distortions; Performance; Phantom Limb Pain; Population; Prevalence; Process; Recruitment Activity; Rehabilitation therapy; Reporting; Research; Retina; Retinal; Somatosensory Cortex; Syndrome; Tactile; Thick; Time; Trauma; Traumatic Brain Injury; Veterans; Vision; Visual Cortex; Visual Cortex Disorder; Visual Fields; Visual Hallucination; Visual Motion; War; Work; autism spectrum disorder; experience; insight; interest; relating to nervous system; response; retinal damage; sample fixation; somatosensory; theories; visual process; visual processing; visual stimulus

The primary goals of this research are i) to establish the changes in brain processing arising from nervous system damage or dysfunction, ii) to understand how brain plasticity contributes to these changes, and iii) to determine how learning may ameliorate the negative consequences of such changes. Over the past year we have continued to focus primarily on plasticity following the loss of input to particular regions of the brain, including visual and somatosensory cortex. i) Loss of visual input. People with macular degeneration lose central vision due to retinal damage. But what happens to the parts of the brain that are specifically involved in processing central visual stimuli? Using fMRI, we have previously shown that the parts of the brain deprived of input start to respond to visual stimuli in other regions of the visual field, as if they are taking on new function. We have referred to this as reorganization of visual processing. We have further demonstrated that such reorganization is dependent on complete loss of central vision, is not specific to the part of the retina used for fixation in people with macular degeneration (often referred to as the Preferred Retinal Locus, or PRL), and may lead to perceptual distortions. We are currently investigating the impact of vision loss in macular degeneration on cortical thickness. In some developmental visual disorders, the cortex has been reported to be thinner than in healthy control participants, but it is unknown whether such structural changes also occur when the vision loss happens in adulthood. ii) Loss of somatosensory input. Following limb amputation, over 90% of people report phantom sensations in their missing limb, often painful sensations (Phantom Limb Pain, or PLP). One current theory suggests that PLP is a direct result of cortical reorganization, an example of maladaptive plasticity. Mirror therapy has been used as a treatment for PLP. During this therapy, patients move their intact limb while looking in a mirror, making it seem as if their missing limb is moving. We are currently investigating the neural consequences of amputation and the impact of mirror therapy on brain activity over time. We are continuing to recruit unilateral limb amputees and monitoring brain activity with fMRI over a period of four weeks while the amputees undergo mirror therapy. We are trying to establish whether the presence of PLP correlates with cortical reorganization in the somatosensory and motor cortex (similar to that observed in our participants with macular degeneration) and whether the mirror therapy works by reducing the extent of cortical reorganization. In addition, we have been investigating motion processing and decision-making in Autism Spectrum Disorders (ASD), processes that are supported by a well-characteristic brain network. Previous studies have reported conflicting results with some studies finding impaired motion processing in ASD and other finding no impairment. By varying the time allowed to make judgments, we find that motion processing in ASD is impaired, but only at short durations. Further, this deficit in performance is reflected in the activity of brain regions involved in visual motion processing, with reduced responses in autistic compared with control participants. Establishing the nature, degree and consequences of plasticity in the adult cortex provides important insights into the potential for rehabilitative brain therapies following injury or dysfunction in the nervous system.

这项研究的主要目标是i）确定由神经系统损害或功能障碍引起的大脑处理的变化，ii）了解大脑可塑性如何对这些变化有何贡献，iii），以确定学习如何改善这种变化的负面后果。在过去的一年中，我们继续主要关注对大脑特定区域（包括视觉和体感皮质）输入输入后的可塑性。 i）视觉输入的丢失。黄斑变性的人由于视网膜损害而失去中央视力。但是，专门处理中央视觉刺激的大脑部分会发生什么？使用fMRI，我们以前已经表明，剥夺输入的大脑部分开始对视野其他区域的视觉刺激做出反应，就好像它们正在携带新功能一样。我们将其称为视觉处理的重组。我们进一步证明，这种重组取决于中央视力的完全丧失，并不是针对黄斑变性的人（通常称为首选的视网膜基因座或PRL）的视网膜固定部分的特定部分，并且可能导致感知失真。我们目前正在研究黄斑变性对皮质厚度的影响。在某些发育视觉障碍中，据报道，皮层比健康对照参与者更薄，但是当视力丧失在成年期发生时，这种结构性变化是否也发生。 ii）损失体感输入。肢体截肢后，超过90％的人报告了肢体缺失的幻影感觉，通常是疼痛的感觉（幻影肢体疼痛或PLP）。当前的一种理论表明，PLP是皮质重组的直接结果，这是适应不良可塑性的一个例子。镜像疗法已被用作PLP的治疗方法。在这种疗法期间，患者在镜子里看着肢体时移动完整的肢体，使他们的肢体看上去似乎在移动。我们目前正在研究截肢的神经后果以及镜像疗法随着时间的推移对脑活动的影响。我们将继续在四个星期内通过fMRI募集单侧肢体截肢者，并通过fMRI监测大脑活动，而截肢者接受镜像治疗。我们正在尝试确定PLP的存在是否与体感和运动皮质中的皮质重组相关（类似于在黄斑变性的参与者中观察到的，以及镜像治疗是否通过减少皮质重组的程度来起作用。 此外，我们一直在研究自闭症谱系障碍（ASD）的运动处理和决策，这些过程由特征性的大脑网络支持。先前的研究报道了矛盾的结果，一些研究发现ASD的运动处理受损，而其他发现没有损害。通过改变允许做出判断的时间，我们发现在ASD中进行的运动处理受损，但仅在短时间内。此外，这种性能的不足反映在与对照参与者相比相比，自闭症的大脑区域的活性减少了自闭症的反应。 建立成人皮层中可塑性的性质，程度和后果，为神经系统受伤或功能障碍后的康复脑疗法的潜力提供了重要的见解。